William Helfand began buying medically themed collectibles in the 1950s when he started working for Merck & Co. Over his 30-year career with the company, Helfand amassed thousands of posters and other old marketing paraphernalia, which were commissioned by pharmacists to promote the supposed medical benefits of products they had developed. A chemical engineer by training, Helfand eventually became involved in marketing and sales at Merck, and initially considered using some of the old posters to inform the company’s advertising because they were so arresting. “I’ve always had a feeling in my heart that the people in the past who did this were my figurative ancestors,” he told Philadelphia Museum of Art, which recently opened an exhibition on the posters. “These were the people who preceded me and the work I was doing.”
But he eventually decided against it. “I felt that the products we had were for today,”...